1. Field of the Invention
This invention relates to improvements and modifications in a mold-supporting arrangement in molding machines and specifically to molding machines used to mold rubber. Though disclosed in connection with the molding of rubber, the invention is applicable to the molding of other materials as well.
2. Description of the Prior Art
U.S. Pat. Nos. 4,459,909 to Takagi, 4,301,673 to Yonezawa; and 4,317,358 to Yonezawa et al, each disclose a molding press machine which includes roller arrangements to permit the molds or dies to be transported smoothly into and out of the press with a minimum of effort and a minimum of damage to the press. Applicant recognizes that in the usual rubber molding procedures, the molds are first loaded with rubber and then pushed into the molding press. The press is closed, the mold compressed, and, after curing, the press is opened and the mold withdrawn. In the larger presses, the molds are heavy and cumbersome to handle. Sliding the molds into and out of the press causes scoring, galling, and denting to the upper surface of the bottom platen of the press and to the undersurface of the mold. As disclosed in the aforementioned United States patents, the molds are more easily moved with reduced damage if load bearing units such as rollers or balls are employed as shown in the Yonezawa et al, U.S. Pat. No. 4,317,358. One of the problems associated with die-rollers which incorporate spring supported balls, is the lack of linear guidance and the consequent "drift" and "yaw" of the molds. Auxiliary guide systems which are proposed by Yonezawa et al. are complex additions to the basic invention.
As noted in my aforementioned copending application, apertures are formed in the lower platen of the press, each aperture being capable of receiving a loadbearing unit in the form of a spring-loaded roller wheel which projects approximately one-sixteenth inch above the top surface of the bottom platen of the press. Spring-loaded roller wheels are inserted into all or less than all of the apertures in the mold plate. The number of rollers used will depend upon the type of mold to be moved in and out of the press. Use of a sufficient number and pattern of the spring-loaded roller wheels enables the mold to be rolled into and out of the press across the top of the bottom platen without scratching the top surface of the bottom platen of the press or the undersurface of the mold. This therefore adds to mold life as well as the life of the platen and it reduces molder fatigue.
The load-bearing unit of my invention is formed of an axle-mounted roller-wheel where a portion of the axle extends through the roller and beyond the periphery of the axle support. This extended axle portion interfits within a portion of the aperture in the platen into which the unit is inserted so as to limit the ability of the unit to rotate in the aperture or to develop undesired play as noted by Yonezawa et al. In addition, the roller I employ does not score or engrave the mold in the undesired manner in which Yonezawa et al describe the spring-loaded ball arrangement.
My roller arrangement limits the ability of the molds to move in undesired directions as my rollers can rotate in only a forward and backward direction.